Dust in the Sahel

Sahel MapI wrote a piece in Sunday’s newspaper about new work by Ben Cook at NASA Goddard and his colleagues about the role of dust in the Dust Bowl drought. As the name implies, we knew the Dust Bowl was dusty. The new bit here is a much more clear understanding of the role of dust in suppressing rain – a feedback between human farming practices and enhanced drought.

One question I kept asking Ben and everyone else I talked to about the paper: What does this mean in the Sahel? Tomorrow in Water Resources Research, Wanching Jacquie Hui and colleagues (including Ben) offer a first cut at an answer:

We investigate the relationship between dust aerosols and rainfall in the West African Sahel where the dust-rainfall feedback has been speculated to contribute to sustained droughts. We find that the amount of dust loadings is negatively correlated with rainfall values, suggesting that dust entrained in the atmosphere can significantly inhibit rainfall in this region.

Here in the United States, changes in farming practices instituted in the depths of the Dust Bowl have largely eliminated the sort of bonkers dust storms seen then. Less ground is left uncovered today. But questions have long been raised about the relationship between long-standing farming practices in the Sahel and drought over the last nearly half century. This paper doesn’t answer the question directly (it does not address the relationship between farming practices and drought directly), but it is one more piece of the puzzle in this particularly precarious part of the world.
(More reading: Wikipedia on Sahel drought)


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